Benign prostatic hyperplasia (BPH) is the most common affliction of men over the age of 50. Traditionally associated symptoms are felt to be secondary to either obstruction or dynamic tone of the smooth muscle of the prostate. To date, there have been no long-term studies of the association between bladder function and prostatic obstruction. The standard urodynamic investigation of drug effects on obstructed voiding function has been uroflowmetry. However, the specificity of impaired flow on bladder obstruction is poor and specific investigations of drug induced changes in outflow conditions need combined pressure/flow studies. Urodynamic evaluation of detrusor pressure/flow studies before and during therapy has been poorly characterized after pharmacologic intervention. The goals of this clinical trial are to determine changes in bladder function as determined by synchronous pressure/flow urodynamics in patients with BPH treated pharmacologically with alpha blockers or 5alpha-reductase inhibitors. Four treatment groups will be studied, 1) placebo, 2) 5 mg of finasteride (PROSCAR), 3) 10 mg of terazosin (HYTRIN) and, 4) 5 mg finasteride and 10 mg of terazosin. Parameters to be analyzed include peak detrusor pressure during voiding, detrusor pressure during maximal power and the detrusor contractility factor, WF. Pre-therapy detrusor contractility will be assessed to determine prognostic significance when correlated with improvement in symptoms. Efficacy as determined by symptom score analysis and uroflow, and safety, as determined by incidence of side effects will be determined. Through this pilot study, we hope to ascertain 1) those contractility parameters which change after pharmacologic treatment of BPH, 2) those parameters which may predict improved outcome to pharmacologic agents. Furthermore, this pilot project will serve as a template for long-term evaluation of detrusor function in untreated and treated patients with BPH as well as prognostic significance of variations in detrusor pressure.